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charset="utf-7" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: db3e0302-022b-4469-110d-08d6b928d9cd X-MS-Exchange-CrossTenant-originalarrivaltime: 04 Apr 2019 18:10:42.1588 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR15MB2822 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-04_09:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org +/v8-On 4/4/19, 10:53 AM, +ACI-David Miller+ACI- +ADw-davem+AEA-davemloft.n= et+AD4- wrote: From: +ACI-Tilmans, Olivier (Nokia - BE/Antwerp)+ACI- +ADw-olivier.tilm= ans+AEA-nokia-bell-labs.com+AD4- Date: Thu, 4 Apr 2019 12:24:02 +-0000 =20 +AD4- RFC8257 +AKc-3.5 explicitly states that +ACI-A DCTCP sender MUST = react to +AD4- loss episodes in the same way as conventional TCP+ACI-. ... +AD4- This patch replace the clamping of alpha by setting ssthresh to +AD4- half of cwnd for both fast retransmissions and RTOs, at most once +AD4- per RTT. Consequently, the dctcp+AF8-clamp+AF8-alpha+AF8-on+AF8-l= oss module parameter +AD4- has been removed. =20 Applied to 'net' and queued up for -stable, thanks. =20 DCTCP is meant to be used in environments where the switches/routers do ECN= marking, so it is not surprising that it performs badly when used in envir= onments where it was not meant to be used. Has anyone measured the effect o= f this changed when DCTCP is used in environments where all the switches/ro= uters do ECN marking? My concern is that we could end up hurting performanc= e when DCTCP is used how it was meant to be used in order to protect incorr= ect uses of DCTCP.